Apparatus for the production of hot reducing gases



Dec. 3,1935. 7 7 c. G. 'MAIER 2,022,773

- APPARATUS FOR THE PRODUCTION OF HOT REDUCING GASES Filed Jan. 18, 19352 Sheetst 2 17mm pm mmo 712M" Patented Dec. 3, 1935 more STATES,

APPARATUS FOR THE PRODUCTION OI HOT REDUCING GASES Charles G. Dialer,Berkeley, Calif alilgnor to Thomas B. Swift Application January 18,1988. Serial No. 652,371

to heated metallurgical reducing gas and will be descrihed andillustrated in that relation, it being apparent that it is equallyadapted to theconversion of any hydrocarbon or mixture, whether normallygaseous or rendered gaseous by heat, it -and that the gas produced mayhe used for other purposes. This application is a continuation-inpert 9frny application'Serial No. 609.965, filed May "7, i932, in that itcontains disclosure and claims divided out of said application, togetherwith disclosure of and claims to certain modiil= cations of saidapparatus.

The principal fault of reducing gas mixtures consisting essentially ofhydrogen and carbon monoxide heretofore produced from natural gas andsimilar hydrocarbons is that they contain amounts of the higheroxidation products, water and carbon dioxide, which render such gasmixtures unfit for certain metallurgical purposes, such as the reductionof iron ore to sponge iron.

The carbon dioxide and water could be removed from the gas mixture bypurification, but this operation is relatively expensive. An object ofmy invention, therefore, is to so conduct the oxidation, of thehydrocarbon that a gas mixture substantially free of water vapor andcarbo dioxide is produced directly.

The process which is carried out in the appa- I other suitable oxygencontaining gas, e. g. oxygen enriched air, with the gaseous hydrocarbonin substantially the proportions theoretically necessary to yield thedesired reaction products, and while maintaining the velocity of thegases greater than the flame propagation rate, passing the mixture intoa granular catalyst or contact mass and regulating the contact of thegases therewith in such manner as to prevent zoning of the oxidationreactions within the mass. It is quite important to avoid combustion orflame. The gas mixture produced contains, of course, the nitrogenderived from the air as a chemically inert but heat carrying ingredient.

The apparatus is illustrated in the accompany- 56 log drawings, inwhich:

Fig. 1 is a vertical section with parts appearing in elevation of oneform of apparatus embodying my invention;

Figs. 2, 3, 4 and 5 are horizontal sections 01' the apparatus shown inFig. l on the lines 2-2, 3-3, s M and 5-4, respectively;

Fig. 6 is a vertical section of a modification of. the apparatusillustrated'in Figs. 1-5;

Fig. 7 is a horizontal section on the line Tl-l oi Fig. t; it Fig. 8 isa vertical section or an apparatus in which a plurality oi the unitsillustrated in Fig. 6

are combined, and

Fig. e is a horizontal section on the line ll-i3 of Fig. it. ill IReferring to Figs. Ii-5 oil the drawings, (1 is the air supply pipe andi the gas supply pipe, both narrowed to nozzles at their inner endswhere they enter the substantially spherical mixing chamber 3 formed inthe body oi refractory ma- 20 terial i. The pipe i is surrounded by thepipe 5 which is provided with on entering flue t for flame or hotcombustion gases. The refractory mass 6 is formed within the shellcomprising the side wall l having an opening to receive the pipe 2, the25 end Wall 8 having an'opening to receive the pipe 9 and the grating 9.The pipes i, 2 and t, flue 6, the side wall l, and wall 8 and grating 9preferably are formed of a suitable refractory alloy such as thewell-known chrome-nickel steels. The refractory mass 4 may be formed orany suitable material, such as crystalline alumina or magnesia cementmolded or tamped into place so as to surround the ends of the pipes land 2 and leave the spherical cavity 3 and the semi-ellip- 35 soidalcavity i! which communicate through the Directly below the orifice I lwithin the cavity it is the deflector I2 which is thimble shaped andformed of suitable refractory material, such as magnesia cement. Gasesleaving the chamber 3 through the orifice H pass into the cavity of thedeflector l2 and flow over its upper edge and then downwardly throughthe porous catalytic mass it. The deflector I2 is supported in thecatalytic mass I: which fllls the cavity so 45 excepting the spacewithin the deflector l2 and above its upper edge. The catalytic mass 03may be any suitable oxidation catalyst, such as a granular refractorymaterial, e. g. porous crystal- 50 line alumina impregnated with nickelsalts or nickel oxide; The whole structure above described is surroundedby the refractory and heat insulating mass I.

The form of apparatus ilmstrated in Figs. 6

and 7 diflers from the apparatus illustrated in Figs. 1 to 5 principallyin that the mixing chambar 3 is dispensed with. Other diiferences in thedetails of construction will appear from the 101- lowing description:

Referringto Figs. 6 and 7, the apparatus comprises an outer insulatingwall I! surrounding a substantially cylindrical shaft, the upper portionof which is walled by the refractory shell l8 and the lower portion ofwhich is lined by the shell of refractory alloy, such as chrome nickelsteel II. The lower end of the shell I! is closed by the grating I8 andcommunicates with the funnel shaped member l9 designed to deliver thegases into a tubular conduit (not shown). Air is supplied through andpreheated in pipe 20 by heating gases supplied through the flue 2|. Theheated air enters the open upper end of the pipe 22 and passingdownwardly therethrough mixes with the hydrocarbon gas supplied throughthe pipe 23. The mixture discharges from the pipe 22 through the orifice24 into the cavity of the thimble shaped deflector 25. The thimble 25 issupported in and surrounded by the catalytic or contact material 26which also supports and surrounds the inverted cup shaped member 21 andfills the space within the shell lI up to the wall 28. The member 21like the thimble 25 is made of refractory material. It contains theorifice 24 and is so shaped and positioned with respect to the thimble25 as to provide a passageway for the gases through the contact material26 of progressively increasing cross-sectional area. As will beapparent, the apparatus illustrated in Fig. 6 functions in substantiallythe same manner as the apparatus of Fig. l, the differences beingdifferences of construction only. v

The apparatus illustrated in Figs. 8 and 9 is a grouping of seven of theunits shown in Egs. 6 and '7 within a single outer wall Ill. The unitshave in common the wall It, shell l6, shell 11, grating i8, funnel l8,catalytic mass 26 and wall In the operation of the apparatus illustratedin Figs. 1 to 5, hydrocarbon gas and preheated air enter the chamber 3through pipes 2 and I, the

air being preheated to a temperature of 800-1000 C. by hot combustiongases or flame entering through the pipe 6 and passing up through thepipe 5 in contact with the pipe I. The nozzle ends of pipes l and 2 aremade of such size that they deliver the gas and air into the chamber 3in proper proportion and at a velocity exceeding the adjacent wall ofthe cavity i8 are such that the flow of the gases exceeds the flamepropagation rate until the gases reach a point about half. way down theouter wall of the deflector i2 in the catalytic mass. Under theseconditions it is found that reaction zones and zones of concentration ofheat do not occur, there is no local overheating and destruction of thecatalytic mass and other parts of the apparatus, and secondary reactionsconverting any carbon diomole and W8,-

terresulting from the primary reaction into carbon monoxide and hydrogenare completed.

The deflector l2 pertorms several important functions. As indicatedabove it plays a quite important part in the mixing of the gas and air.In 5 starting the apparatus a flame is apt to be formed at the oriflceii and the deflector protects the catalytic mass from this flame untilthe operation is properly adjusted. An exothermic reaction occurs in thecavity of the deflector and the heat of this reaction is harmlesslytransmitted through the mass of the deflector to the catalytic mass. Italso serves to catch dirt'particles accidentally in the air and gas andprevent them e from depositing upon the catalytic mass and clogging itspores. An important feature of the invention is that the mixture of airand gas is brought into contact with the porous catalytic mass atreacting temperature, but without flame, i. e. at a velocity higher thanthe velocity of flame propagation, and then gradually slowed down withinthe catalytic mass by virtue of its shape, i. e. its graduallyincreasing cross-section in the path of the gases. As a result theexothermic and endothermic stages of the reaction take place virtuallysimultaneously and the zoning with overheating at one point and adeficiency of heat for completing the reaction at another point in thecatalytic mass is avoided. As is evident, if the highly exo- 30 thermicstage of the reaction were permitted to take place before the gasmixture reached the catalytic mass the result would be a flame whichwould strike the catalytic mass anddestroy it.

On the other hand, if the high velocity of the Otherwise the operationof this apparatus is the same as that illustrated in Figs. 1 to 5. Theoperation of the multiple unit embodiment illustrated in Figs. 8 and 9will be apparent from the foregoing description or the operation of thesinsl'e unit.

The following specific conditions of operation are illustrative. Thepipe I is made of 10 gauge alloy steel 2 inches in diameterand 5 feetlong, nozzled at one end to an orifice V inchin diameter. The pipe 2 isofthe same material and diameter, but nozzled to a inch orifice. Thechamber 3 is 1 inches in diameter and the orifice II is A inch indiameter. The cavity I0 is 7 inches long and 6 inches in diameter at thegrating 9. The deflector thimble is 3% inches long, 1% inches maximuminternal diameter and 2% inches maximum external diameter. The catalystis crystalline alumina 01' 4 to 10 mesh size impregnated with nickel.Air is delivered into the chamber 3 at 900 C. and at the rate of 100liters per minute and natural gas is delivered at the rate of 35 litersper minute, both gas and air under a gauge pressure of about 2 poundsper square inch. The gas passing out through the grating 9 is at atemperature of 1050-1100 C. The analysis of the natural gas used is:

v Percent Methane 86.85 Ethane (CzzHa) 7.86 Propane (Cal-Is) 3.87

H gher parse hydrocarbons 1.47

The gas produced is of the following composition:

Percent Methane (CH4) 0.5 Carbon dioxide (CO 0.9 Water (H2O) 0.9 Carbonmonoxide (CO) 19.3 Hydrogen (H2) 36.4 Nitrogen 41.9

' general it is possible to produce a gas at a temperature in theneighborhood of 1000 C. containing negligible amounts of hydrocarbon,and the higher oxidation products, water vapor and carbon dioxide, andconsisting essentially of carbon monoxide and hydrogen with nitrogen.

It will be understood that the operation of my apparatus avoids the useof an excess of air for supplying the necessary heat for carrying on thereaction by combustion with consequent pollution of the gases-withcombustion products as in certain prior attempts to produce acombustible or reducing gasmixture by the partial oxidation ofhydrocarbons in the presence of catalysts. I-supply the necessary heatwithout the use of an excess of air by preheating the air supply, and Iavoid the difliculty heretofore encountered by others in preheating theair supply, e. g. that excessively high local temperatures are producedin the catalytic mass, by intimately mixing the reacting gases andpassing the mixture to and through the catalytic mass at such aregulated speed that the exothermic and endothermic stages of thereaction occur essentially together in the absence of flame so thatspatially separated zones of reaction are avoided. A temperature of atleast about 1000 C. is maintained in the catalytic mass and the airsupply is heated to about 800-1000 C.

It is observed that the essential characteristics of the apparatusillustrated and described above may be preserved while making certainchanges in the details of construction without departing face at thelocation of its smallest cross-sectional area, and means for supplying ahighly heated mixture of hydrocarbon gas andoxygen containing gas tosaid catalytic mass through said free surface comprising separateconduits for the oxygen containing gas and the hydrocarbon gas, meansfor heating the conduit for the oxygen containing gas, means forbringing said oxygen containing gas and hydrocarbon gas together at highvelocity, means for delivering a stream of the resuiting gas mixture athigh velocity to said catalytic mass and means for preventing directimpingement of said stream directly upon the catalytic mass.

2. Apparatus for the controlled oxidation of hydrocarbons comprising aporous refractory catalytic mass of progressively increasingcrosssectional area throughout its length in the directionof flow ofgases therethrough, separate supplies of hydrocarbon gas and air, meansfor heating the air supply, means for intimately mixing thehydrocarbonand air, means for delivering a stream of the resulting mixture to thecatalytic mass, and a deflector preventing impingement of said streamdirectly upon the catalytic mass.

3.- Apparatus for the controlled oxidation of hydrocarbons as defined inclaim 1 in which said means for intimately mixing the hydrocarbon andair comprises nozzled conduits delivering into a substantially sphericalmixing chamber.

4. Apparatus for the controlled oxidation of hydrocarbons as defined inclaim 1 in which the means for mixing the hydrocarbon and air comprisesnozzled conduits delivering into a substantially spherical mixingchamber, and an orifice in said chamber through which the gas mixture isdelivered to the catalytic mass.

5.'Apparatus as defined in claim 2 in which the deflector is thimbleshaped with is convex side in contact with the catalytic mass and itsconcave 40 side in the line of movement of said stream.

6. Apparatus for the controlled combustion of hydrocarbons comprising aporous catalytic mass, a thimble shaped member formed of imperviousrefractory material having its convex side only 46 in contact with saidmass, a cup shaped member formed of impervious refractory materialpositioned with its concave side opposed to the concave side of saidthimble shaped member and its side walls overlapping the side walls ofsaid 50 thimble shaped member, the space between said walls defining aspace filled with catalytic mass of progressively increasingcross-sectional area and, an opening'in one of said members for theintroduction of a fluid stream into the space de- 56 fined by theopposed concave surfaces of said members.

CHARLES G. MAIER.

